Laminated film, optical member, and image display device

Abstract

To provide a laminated film which has superior hard coat performance and superior bendability, and which is capable of suppressing crack formation even under bending.SOLUTION: A laminated film according to an embodiment of the present invention includes a substrate and a hard coat layer disposed on one surface of the substrate. The substrate includes a first resin layer and a second resin layer, arranged sequentially from the hard coat layer side. A difference in a solubility parameter between the hard coat layer and the first resin layer is 1.5 or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a laminated film, an optical member, and an image display device.

Background Art

[0002] Image display devices typified by liquid crystal display devices and electroluminescence (EL) display devices (for example, organic EL display devices and inorganic EL display devices) have been rapidly spreading. In organic EL display devices, there is an increasing demand for improved flexibility such as flexibility that can be bent flexibly, foldability that can be folded, and bendability that can be curved. On the other hand, a hard coat layer may be provided on the viewing side of the display device to prevent scratches, breakage, etc. In this case, typically, a laminated film having a base material and a hard coat layer can be used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the laminated film (hard coat film) used for an organic EL display device that requires flexibility is bent, cracks may occur.

[0005] An object of the present invention is to provide a laminated film that is excellent in hard coat properties and flexibility and can suppress the occurrence of cracks even when bent.

Means for Solving the Problems

[0006] [1] The laminated film according to an embodiment of the present invention includes a base material and a hard coat layer disposed on one surface of the base material. The base material includes a first resin layer and a second resin layer in this order from the hard coat layer side. The difference in solubility parameters between the hard coat layer and the first resin layer is 1.5 or more. [2] In the laminated film according to [1] above, the second resin layer may be directly disposed on the first resin layer. [3] In the laminated film according to [1] or [2] above, the hard coat layer may be directly disposed on the first resin layer. [4] In the laminated film according to [1] to [3] above, the difference in glass transition temperature between the first resin layer and the second resin layer may be 40°C or less. [5] In the laminated film according to any one of [1] to [4] above, the second resin layer may contain a polycarbonate resin. The polycarbonate resin may contain a structural unit derived from a dihydroxy compound. The dihydroxy compound may be at least one compound selected from the group consisting of isosorbide, isomannide, and isoidide. [6] In the laminated film according to any one of [1] to [5] above, the first resin layer may contain a polycarbonate resin. The polycarbonate resin in the first resin layer may not substantially contain a structural unit derived from a dihydroxy compound selected from the group consisting of isosorbide, isomannide, and isoidide. [7] In the laminated film according to any one of [1] to [6] above, the thickness of the first resin layer may be smaller than the thickness of the second resin layer. [8] In the laminated film according to any one of [1] to [7] above, the thickness of the first resin layer may be 0.5 μm or more and 10 μm or less. [9] In the laminated film according to any one of [1] to [8] above, the thickness of the second resin layer may be 15 μm or more and 40 μm or less.

[10] An optical member according to another aspect of the present invention includes the laminated film according to any one of [1] to [9] above and an optical film.

[11] In the optical member according to

[10] above, the optical film includes a polarizer.

[12] An image display device according to another aspect of the present invention includes the laminated film according to any one of [1] to [9] above.

[13] An image display device according to another aspect of the present invention includes the optical member according to

[10] or

[11] above.

Effects of the Invention

[0007] According to an embodiment of the present invention, it is possible to realize a laminated film that is excellent in hard coat properties, excellent in flexibility, and can suppress the occurrence of cracks even when bent.

Brief Description of the Drawings

[0008]

Figure 1

Modes for Carrying Out the Invention

[0009] Hereinafter, representative embodiments of the present invention will be described, but the present invention is not limited to these embodiments. Also, for the purpose of making the description clearer, the drawings may schematically show the width, thickness, shape, etc. of each part as compared with the embodiments, but this is merely an example and does not limit the interpretation of the present invention. In this specification, "A and / or B" means any one of "A", "B", and "A and B".

[0010] A. Overall Configuration of the Laminated Film FIG. 1 is a schematic cross-sectional view of a laminated film according to one embodiment of the present invention. The laminated film 1 in the illustrated example includes a hard coat layer 10 and a base material 20. The hard coat layer 10 is disposed on one surface of the base material 20. The base material 20 includes a first resin layer 21 and a second resin layer 22, and the first resin layer 21 is disposed on the hard coat layer 10 side. That is, the laminated film 1 includes the hard coat layer 10, the first resin layer 21, and the second resin layer 22 in this order. In the laminated film 1, the difference in solubility parameters between the hard coat layer 10 and the first resin layer 21 is 1.5 or more.

[0011] The laminated film according to the embodiment of the present invention can maintain high hard coat properties as a hard coat film, achieve high flexibility when bent, and suppress the occurrence of cracks even when bent.

[0012] Conventionally, in a laminated film provided with a hard coat layer, there has been a problem that it is difficult to achieve both hard coat properties and flexibility. A laminated film having a conventional use as a hard coat film is formed of a two-layer structure of a base material and a hard coat layer. Such a laminated film having a two-layer structure may crack when bent even when using a base material having excellent flexibility.

[0013] As a result of intensive studies, the present inventors have found that cracks generated in the laminated film can be attributed to a compatible layer formed at the interface between the base material and the hard coat layer. The compatible layer is a layer in which components of the base material and the hard coat layer are mixed and has insufficient mechanical strength. As a result, when the laminated film is bent, cracks can occur starting from the compatible layer. Therefore, the present inventors continued intensive studies to suppress the generation of the compatible layer and completed the laminated film according to the embodiment of the present invention.

[0014] That is, in the laminated film according to the embodiment of the present invention, it has a three-layer structure including a base material containing a first resin layer and a second resin layer and a hard coat layer, and the difference in solubility parameters between the hard coat layer and the first resin layer disposed on the hard coat layer side is 1.5 or more. By adopting such a configuration, the formation of a compatible layer can be suppressed between the hard coat layer and the base material (substantially the first resin layer). Further, the first resin layer intervening between the hard coat layer and the second resin layer can also function as a protective layer for protecting the second resin layer. As a result, the laminated film according to the embodiment of the present invention can maintain high hard coat properties, improve flexibility, and suppress the occurrence of cracks even when bent. Note that such a mechanism is merely speculative and does not restrict or limit the interpretation of the present invention.

[0015] In this specification, the "difference in solubility parameters between the hard coat layer and the first resin layer" is the absolute value of the difference between the solubility parameter of the hard coat layer (the material forming the hard coat layer) and the solubility parameter of the first resin layer (the material forming the first resin layer). The solubility parameter is the square root of the molecular cohesive energy density and is also represented as δ. Specifically, the solubility parameter δ of a certain substance is defined by the following formula when the molar volume is V and the cohesive energy per mole is ΔE. δ = (ΔE / V) 1 / 2 The solubility parameter may also be referred to as the sp value. The unit of the sp value is MPa 1 / 2 The sp value of the hard coat layer and the sp value of the first resin layer are calculated based on Fedors' sp value estimation method.

[0016] In the laminated film according to the embodiment of the present invention, the hard coat layer can be directly disposed on the first resin layer. With such a configuration, the laminated film according to the embodiment of the present invention can maintain high flexibility well because the formation of a compatible layer is suppressed as described above while maintaining high hard coat properties. "Directly disposed" in this case means that no adhesive layer (adhesive layer or pressure-sensitive adhesive layer) intervenes between the first resin layer and the hard coat layer.

[0017] In the laminated film according to an embodiment of the present invention, the first resin layer can be directly disposed on the second resin layer. With such a configuration, the laminated film according to the embodiment of the present invention can achieve better flexibility while maintaining high hard coat properties. Further, with such a configuration, it can particularly contribute to the thinning of the laminated film according to the embodiment of the present invention. The "direct disposition" in this case means that no adhesive layer (adhesive layer or pressure-sensitive adhesive layer) is interposed between the first resin layer and the second resin layer. Note that one or more layers may be interposed between the first resin layer and the second resin layer without departing from the object of the present invention.

[0018] The hard coat property of the laminated film according to the embodiment of the present invention can be evaluated by pencil hardness (scratch hardness (pencil method)). Specifically, the pencil hardness of the surface on the hard coat layer side in the laminated film according to the embodiment of the present invention is preferably 2H or more, more preferably 3H or more. The pencil hardness can be measured in accordance with JIS K 5600 5-4.

[0019] The flexibility of the laminated film according to the embodiment of the present invention can be evaluated by performing a bending test. The bending test is evaluated, for example, by performing an MIT test in accordance with JIS P 8115. Specifically, it can be evaluated by the number of repetitions until cracks occur by repeating bending. The laminated film preferably has a flexibility such that no breakage (cracks) is confirmed even when repeated 50,000 times or more, more preferably 100,000 times or more, still more preferably 150,000 times or more, and particularly preferably 200,000 times or more under such conditions.

[0020] The laminated film according to an embodiment of the present invention may preferably have restorability after being bent. The restorability after being bent means that it returns to its original state without leaving a crease after being bent. The restorability after being bent is evaluated, for example, by conducting an MIT test in accordance with JIS P 8115. Specifically, it can be evaluated by the number of repetitions until a crease appears after repeating the bending. The laminated film preferably has a restorability such that it returns to its original state without leaving a crease even when repeated preferably 50,000 times or more, more preferably 100,000 times or more, still more preferably 150,000 times or more, and particularly preferably 200,000 times or more under such conditions.

[0021] The light transmittance of the laminated film according to an embodiment of the present invention is preferably 80% or more, more preferably 85% or more, and still more preferably 90% or more. The light transmittance can be measured in accordance with JIS K 7361-1:1997.

[0022] The haze of the laminated film according to an embodiment of the present invention is preferably 5% or less, more preferably 3% or less, and still more preferably 1% or less. The haze can be measured in accordance with JIS K 7136:2000.

[0023] Hereinafter, each member that can constitute the laminated film according to an embodiment of the present invention will be specifically described.

[0024] B. Hard coat layer In this specification, the "hard coat layer" is used as a general term for a hard surface treatment layer having a surface protection function. Therefore, the hard coat layer can include not only a general hard coat layer but also an antireflection layer, an anti-sticking layer, an antiglare layer, and an antiblocking layer.

[0025] The hard coat layer can be composed of any suitable material. In the laminated film of the present embodiment, as described above, the difference in the sp value between the hard coat layer and the first resin layer in the base material may be 1.5 or more. Therefore, as a material that can form the hard coat layer, any suitable material can be selected as long as the difference from the sp value of the first resin layer is 1.5 or more. The sp value of the hard coat layer is the sp value of the material that can form the hard coat layer. The sp value of the first resin layer is the sp value of the material that can form the first resin layer.

[0026] Examples of the material that can form the hard coat layer (hereinafter sometimes referred to as "material for forming the hard coat layer") typically include thermosetting resins and active energy ray (e.g., ultraviolet ray, visible light ray, electron beam) curable resins. As such curable resins, for example, curable compounds having a (meth) acrylate group that are cured by heat, light (such as ultraviolet ray), or electron beam can be employed. In this specification, "(meth) acrylate" means "methacrylate" and / or "acrylate".

[0027] Specific examples of the curable resin include silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and oligomers or prepolymers of acrylates and methacrylates of polyfunctional compounds such as polyhydric alcohols. These may be used alone or in combination of two or more. Commercially available products may be used as the curable resin.

[0028] The material for forming the hard coat layer may contain, for example, at least one of (meth) acrylic resins, urethane (meth) acrylates, and copolymers of oligomers and monomers having functional groups. Examples of the monomer having a functional group include polyfunctional (meth) acrylates. The (meth) acrylate is preferably bifunctional or more, more preferably trifunctional or more. Examples of the oligomer having a functional group include curable urethane (meth) acrylates (e.g., sp value 11.25 MPa 1 / 2) can be mentioned.

[0029] The hard coat layer (substantially, the material for forming the hard coat layer) may contain a total of 60 parts by weight or more of curable urethane (meth)acrylate and (meth)acrylate having a functionality of 3 or more with respect to 100 parts by weight of the total resin for forming the hard coat layer. The total amount is preferably 70 parts by weight or more, more preferably 80 parts by weight or more, still more preferably 90 parts by weight or more, and particularly preferably 95 parts by weight or more. The total amount may be 100 parts by weight. That is, all of the material for forming the hard coat layer may be composed of curable urethane (meth)acrylate and / or (meth)acrylate having a functionality of 3 or more. Examples of the curable urethane (meth)acrylate include UV curable urethane acrylate manufactured by Mitsubishi Chemical Corporation (specifically, product name "UV-1700TL"), and product name "UT-7314" manufactured by Mitsubishi Chemical Corporation. Examples of the polyfunctional (meth)acrylate include product name "Unidic (registered trademark) 17-807" manufactured by DIC Corporation, and product name "M-920" manufactured by Toagosei Co., Ltd.

[0030] The above material for forming the hard coat layer may further contain any suitable additive. Examples of the additive include an anti-blocking agent, a dispersion stabilizer, a thixotropic agent, an antioxidant, an ultraviolet absorber, an antifoaming agent, a thickener, a dispersant, a surfactant, a catalyst, a lubricant, an antistatic agent, etc. Further, the above material for forming the hard coat layer may contain any suitable solvent.

[0031] The hard coat layer can be formed, for example, by applying the material for forming the hard coat layer to a coating surface (for example, one surface of the substrate (in the illustrated example, the first resin layer 21)) to form a coating layer, and heating (if necessary) and curing the coating layer.

[0032] As a method for applying the hard coat layer forming material, any appropriate method can be adopted. For example, bar coating method, roll coating method, gravure coating method, rod coating method, slot orifice coating method, curtain coating method, fountain coating method, comma coating method can be mentioned.

[0033] The heating temperature of the coating layer can be set to an appropriate temperature according to the composition of the hard coat layer forming material. The heating temperature is, for example, 50°C to 150°C.

[0034] As for the curing of the coating layer, any appropriate curing treatment can be adopted. Typically, the curing treatment is performed by ultraviolet irradiation. The integrated light amount of ultraviolet irradiation is preferably 100 mJ / cm 2 ~400 mJ / cm 2 is.

[0035] As the hard coat layer, a resin film that can be produced from the hard coat layer forming material may be adopted. The resin film can be produced from any appropriate material. When adopting a resin film, the laminated film according to the embodiment of the present invention can be produced by laminating the resin film on a base material (first resin layer) via an adhesive layer (for example, an adhesive layer, an adhesive layer: not shown). In addition, in this case, any appropriate film can be selected according to the adhesive before curing, the sp value of the first resin layer (the material forming the first resin layer), and the solvent contained in the adhesive.

[0036] When the hard coat layer is laminated on a base material (first resin layer), the hard coat layer is formed in the same manner as above on an arbitrary appropriate transfer base material, then laminated on the base material via an adhesive layer, and then the transfer base material is peeled off and removed, and the transfer to the base material (substantially the first resin layer) is completed. The laminated film according to the embodiment of the present invention may be produced in this way. Note that a compatible layer can be formed at the interface between the adhesive layer and the base material by the adhesive before curing.

[0037] The thickness of the hard coat layer is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more, and particularly preferably 4 μm or more. The thickness of the hard coat layer is preferably 10 μm or less, more preferably 8 μm or less, still more preferably 7 μm or less, and particularly preferably 6 μm or less. If the thickness of the hard coat layer is within such a range, the mechanical strength of the laminated film can be improved, and excellent flexibility can be imparted to the laminated film.

[0038] C. Substrate As described above, the substrate includes the first resin layer and the second resin layer. However, the configuration of the substrate in the laminated film according to the embodiment of the present invention is not limited thereto. For example, in the substrate, any appropriate one or more layers may be interposed between the first resin layer and the second resin layer, and any appropriate one or more layers may be provided on the surface of the second resin layer opposite to the surface on which the first resin layer is disposed. Hereinafter, the first resin layer and the second resin layer will be specifically described.

[0039] C-1. First resin layer The first resin layer can be made of a resin material. As described above, the difference in the sp value between the first resin layer and the hard coat layer is 1.5 or more. Therefore, as the resin material that can form the first resin layer, a material having a difference in the sp value from that of the hard coat layer of 1.5 or more can be selected.

[0040] The resin material for forming the first resin layer (hereinafter sometimes referred to as the "first resin material") may be a material composed of a single resin component or a material (composition) composed of a plurality of components. When the first resin layer is made of a composition, the solubility sp value of the first resin layer means the sp value of the entire composition.

[0041] The first resin material is preferably a thermoplastic resin. Specific examples of the first resin material include, for example, (meth)acrylic resins; cellulose resins such as diacetyl cellulose and triacetyl cellulose; cycloolefin resins such as norbornene resins; olefin resins such as polypropylene; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyamide resins; polycarbonate resins; and copolymer resins thereof.

[0042] Among them, the first resin material is preferably at least one resin material selected from the group consisting of (meth)acrylic resins, cycloolefin resins, and polycarbonate resins. When the first resin material is at least one of the above resins, it is particularly easy to adjust so that the difference in the sp value between the first resin layer and the hard coat layer is 1.5 or more.

[0043] Any suitable resin can be employed as the (meth)acrylic resin. Specifically, the (meth)acrylic resin typically contains, as a main component, repeating units derived from (meth)acrylate monomers having a linear or branched structure. The (meth)acrylic resin may contain repeating units derived from any suitable comonomer according to the purpose. Examples of the comonomer (copolymer monomer) include carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, aromatic ring-containing (meth)acrylates, and heterocyclic ring-containing vinyl monomers. Examples of commercially available products of specific (meth)acrylic resins include the product name HTX-Z (sp value: 9.5 MPa 1 / 2 ) manufactured by Kaneka Corporation, etc.

[0044] Any suitable resin can be employed as the cycloolefin resin. Specifically, examples of the cycloolefin resin include polyolefins having a cyclic olefin skeleton, and more specifically, polynorbornene and the like. Examples of commercially available products of specific cycloolefin resins include the product name ZEONOR (sp value: 8.5 MPa 1 / 2 ) manufactured by Zeon Corporation, etc.

[0045] Examples of the polycarbonate resin include any suitable polycarbonate resin. The polycarbonate resin is a thermoplastic resin having at least one carbonate group (-O=(C=O)-O-) in the molecule. The polycarbonate resin can be synthesized from, for example, a dihydroxy compound and a dialkyl carbonate compound, a diaryl carbonate compound, diphenyl carbonate, etc. Examples of commercially available products of specific polycarbonate resins include the product name Tafron (sp value: 9.7 MPa) manufactured by Idemitsu Kosan Co., Ltd. 1 / 2 ) and the like.

[0046] When the first resin layer is a polycarbonate resin, the polycarbonate resin preferably does not substantially contain a structural unit derived from at least one dihydroxy compound selected from the group consisting of isosorbide, isomannide, and isoidide. In this case, in the laminated film, the formation of a compatible layer between the hard coat layer and the first resin layer can be particularly well suppressed. As a result, it can particularly contribute to the improvement of the flexibility of the laminated film. In the present specification, the above "not substantially contain" means that the proportion of the structural unit derived from the above dihydroxy compound in the first resin layer is 1% by mass or less based on the total weight of the first resin layer. The proportion of the structural unit derived from the above dihydroxy compound in the first resin layer is preferably 0.5% by mass or less, more preferably 0% by mass. The total mass of the first resin layer means the total amount of all components excluding volatile components.

[0047] A preferred combination of the hard coat layer (substantially, the material for forming the hard coat layer) and the first resin layer (substantially, the first resin material) is as follows; · Hard coat layer: HEMA (hydroxyethyl methacrylate. sp value 11.25 MPa 1 / 2 ) and the first resin layer: cycloolefin polymer (sp value 8.5 MPa 1 / 2 ), (meth)acrylic resin (sp value 9.5 MPa 1 / 2 ), or polycarbonate resin (sp value 9.7 MPa 1 / 2 ); · Hard coat layer: HPA (hydroxypropyl acrylate. sp value 11.0 MPa 1 / 2 ) and the first resin layer: cycloolefin polymer (sp value 8.5 MPa 1 / 2 ), or (meth)acrylic resin (sp value 9.5 MPa 1 / 2 ).

[0048] The first resin layer may be a single resin film or a multilayer extruded film with the second resin layer. When the first resin layer is a single resin film, it can be produced by any suitable forming method. The first resin layer is preferably a film (multilayer extruded film) formed by multilayer extrusion with the second resin layer. When it is a multilayer extruded film, there is no need to provide an adhesive layer between the first resin layer and the second resin layer, and the adverse effects of the adhesive can be prevented. Furthermore, the first resin layer and the second resin layer (especially the first resin layer) can be thinned down.

[0049] The glass transition temperature of the first resin layer is preferably 110 °C or higher, more preferably 115 °C or higher, and even more preferably 120 °C or higher. The glass transition temperature of the first resin layer is preferably 280 °C or lower, more preferably 175 °C or lower, and even more preferably 170 °C or lower. When the glass transition temperature of the first resin layer is within the above range, the heat resistance can be improved while ensuring the processability of the laminated film.

[0050] The difference in the glass transition temperature between the first resin layer and the second resin layer is preferably 40 °C or lower, more preferably 38 °C or lower, and even more preferably 35 °C or lower. When the difference in the glass transition temperature between the first resin layer and the second resin layer is within the above range, higher heat resistance and higher flexibility of the laminated film can be maintained.

[0051] The thickness of the first resin layer is preferably 10 μm or less, more preferably 7 μm or less, and even more preferably 5 μm or less. The thickness of the first resin layer is preferably 0.5 μm or more, more preferably 1 μm or more. When the first resin layer is produced by multilayer extrusion, it is possible to achieve a thinner thickness that is impossible with a single resin film.

[0052] The thickness of the first resin layer is preferably smaller than the thickness of the second resin layer. In this case, while thinning the laminated film according to the embodiment of the present invention, it can contribute to further improvement in the flexibility of the laminated film.

[0053] C-2. Second Resin Layer The second resin layer can be made of a resin material. The resin material for producing the second resin layer (hereinafter, may be referred to as "second resin material") may be a material composed of one kind of resin, or may be a material (composition) composed of a plurality of components.

[0054] Any suitable material can be adopted as the second resin material. As specific examples, the same resins as those of the first resin material described in Item C-1 can be mentioned. Among them, the second resin material preferably contains a polycarbonate resin. Within the range where the effects of the present invention can be obtained, the polycarbonate resin in the second resin material can adopt the same configuration as the polycarbonate resin described in Item C-1.

[0055] In the laminated film according to the embodiment of the present invention, preferably, the second resin layer contains a polycarbonate resin, and more preferably, the second resin layer contains a polycarbonate resin different from the polycarbonate resin that can be adopted in the first resin layer. When the second resin layer contains a polycarbonate resin different from the polycarbonate resin that can be adopted in the first resin layer, the polycarbonate resin in the second resin layer preferably contains a structural unit derived from a dihydroxy compound. The dihydroxy compound preferably contains a structural unit derived from at least one dihydroxy compound selected from the group consisting of isosorbide, isomannide, and isoidide. With such a configuration, the flexibility of the laminated film according to the embodiment of the present invention can be significantly improved. Isosorbide, isomannide, and isoidide are in a relationship of stereoisomers of the structure shown in the following formula (1).

Chemical formula

[0056] In the polycarbonate resin, it is particularly preferable that the dihydroxy compound contains isosorbide among isosorbide, isomannide, and isoidide. That is, it is particularly preferable that the second resin layer contains a structural unit derived from isosorbide. With such a configuration, the flexibility of the laminated film according to the embodiment of the present invention can be particularly remarkably improved. Moreover, since isosorbide is abundantly present as a resource and is obtained by dehydrative condensation of sorbitol produced from various starches that are easily available, it is excellent in terms of availability, manufacturability, optical properties, and moldability.

[0057] The polycarbonate resin in the second resin layer preferably may have a structure represented by the following formula (2).

Chemical formula

[0058] Details of the polycarbonate resin that can be suitably used for the second resin material and its production method are described in, for example, Japanese Patent Application Laid-Open No. 2014-10291 and Japanese Patent No. 5528606, and the description is incorporated herein by reference.

[0059] In the second resin layer, the proportion of the structural unit derived from the dihydroxy compound is preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 40% by mass or more, and may be, for example, 100% by mass, based on the total mass of the second resin layer. The proportion of the structural unit derived from the dihydroxy compound is preferably 70% by mass or less, more preferably 60% by mass or less, still more preferably 50% by mass or less, based on the total weight of the second resin layer. The total mass of the second resin layer means the total amount of all components excluding volatile components.

[0060] The second resin layer may be a single resin film or a multilayer extruded film with the first resin layer. When the second resin layer is a single resin film, it can be produced by any suitable forming method. Preferably, the second resin layer is a multilayer extruded film with the first resin layer. When it is a multilayer extruded film, it is not necessary to provide an adhesive layer between the first resin layer and the second resin layer, and the adverse effects of the adhesive can be prevented. Furthermore, the first resin layer and the second resin layer (especially the first resin layer) can be thinned, and the second resin layer can also function as a support for the thinned first resin layer.

[0061] The glass transition temperature of the second resin layer is preferably 100°C or higher, more preferably 110°C or higher, and still more preferably 120°C or higher. The glass transition temperature of the second resin layer is preferably 180°C or lower, more preferably 170°C or lower, and still more preferably 160°C or lower. When the glass transition temperature of the second resin layer is within the above range, the heat resistance can be improved while ensuring the processability of the laminated film. The glass transition temperature of the second resin layer is preferably lower than that of the first resin layer.

[0062] The thickness of the second resin layer is preferably larger than that of the first resin layer. The thickness of the second resin layer is preferably 40 μm or less, more preferably 30 μm or less, and still more preferably 20 μm or less. The thickness of the second resin layer is preferably 15 μm or more, more preferably 20 μm or more. In one embodiment, the second resin layer can also function as a support for the first resin layer.

[0063] C-3. Method for Producing Substrate The substrate in the laminated film according to the embodiment of the present invention can preferably be produced by a multilayer extrusion method (also referred to as a coextrusion molding method). Specifically, the production of the substrate by the multilayer extrusion method can be carried out as follows, for example. First, a first resin material and a second resin material are prepared. The first resin material may be in pellet form. The same applies to the second resin material. Subsequently, the first resin material and the second resin material are introduced into the respective inlets of the multilayer extrusion molding apparatus equipped with the inlet for the first resin material and the inlet for the second resin material, and are melted by heating at any appropriate temperature. The resin materials in a pre-heated and melted state (molten state) may be introduced into the inlets. Subsequently, while continuously discharging the first resin material and the second resin material from the respective discharge ports of the multilayer extrusion molding apparatus (equipped with the discharge port for the first resin material and the discharge port for the second resin material), the materials are stretched to a predetermined dimension by a T-die of the multilayer extrusion molding apparatus, and the first resin material and the second resin material are formed into a laminated film shape to obtain a laminate. Subsequently, while transporting the laminate with a roll, the laminate is cooled and solidified at any appropriate temperature. Thereby, a base material in which the first resin layer and the second resin layer are directly laminated is obtained.

[0064] D. Method for manufacturing a laminated film The laminated film according to the embodiment of the present invention can be produced by laminating a hard coat layer, a first resin layer, and a second resin layer in this order. For example, the base material including the first resin layer and the second resin layer can be produced by the above-described multilayer extrusion method. Subsequently, a hard coat layer is disposed on the first resin layer side of the base material including the first resin layer and the second resin layer (that is, on the side opposite to the surface of the first resin layer facing the second resin layer). The hard coat layer is disposed by applying a material for forming the hard coat layer on the first resin layer side of the base material by any appropriate method, and then subjecting the applied coating layer of the material for forming the hard coat layer to any appropriate curing treatment to cure it and produce a hard coat layer as a cured film. Thereby, the laminated film according to the embodiment of the present invention can be obtained.

[0065] Note that the method for manufacturing the laminated film according to the embodiment of the present invention is not limited to the above. The laminated film according to the embodiment of the present invention may be produced by any appropriate method so that the hard coat layer, the first resin layer, and the second resin layer are laminated and arranged in this order.

[0066] E. Optical member Embodiments of the present invention also include an optical member using the above laminated film. The optical member according to an embodiment of the present invention includes the above laminated film and an optical film.

[0067] Examples of the optical film include any suitable optical film. The optical film may be a film composed of a single layer or a laminate. Specific examples of the optical film composed of a single layer include a polarizer and a retardation film. Specific examples of the optical film configured as a laminate include a polarizing plate (specifically, a laminate of a polarizer and a protective film), a conductive film for a touch panel, a surface treatment film, and a laminate appropriately laminated for the purpose of these optical films composed of a single layer and / or optical films configured as a laminate (for example, a circular polarizing plate for antireflection, a polarizing plate with a conductive layer for a touch panel).

[0068] F. Image display device Embodiments of the present invention also include an image display device using the above laminated film or the above optical member. Therefore, the image display device according to an embodiment of the present invention may include the above laminated film or the above optical member. The image display device according to an embodiment of the present invention preferably includes an image display panel and the above laminated film or the above optical member on the viewing side of the image display panel. In the image display device according to an embodiment of the present invention, preferably, the hard coat layer of the laminated film is disposed on the viewing side of the image display panel.

[0069] Examples of the image display device according to an embodiment of the present invention include any suitable image display device. The image display device is, for example, a liquid crystal display device or an organic EL display device, and preferably an organic EL display device. The laminated film according to an embodiment of the present invention can be particularly usefully used for an organic EL display device that is bendable, foldable, or curvable. This is because the effects according to the embodiments of the present invention are remarkable in such a case.

[0070] Note that the use of the laminated film according to the embodiment of the present invention is not limited to the above, and can also be applied to any appropriate optical device or the like.

Example

[0071] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by these examples.

[0072] 1. Evaluation method (1) Hard coat property (scratch hardness (pencil method)) The pencil hardness of the surface on the hard coat layer side of the laminated films obtained in the examples and comparative examples was measured in accordance with JIS K 5600-5-4. (2) Bending test The bendability of the laminated films obtained in the examples and comparative examples was subjected to the MIT test in accordance with JIS P 8115 and evaluated as follows. The laminated film (thickness 0.4 mm) was punched out into a measurement sample (sample) with a length of 100 cm and a width of 29 cm. The sample was set in a MIT folding endurance tester (manufactured by Tester Sangyo Co., Ltd.), and folding was repeated under the conditions of a temperature of 25°C, a folding (bending) radius of curvature R = 1.5 mm, a folding speed of 30 times / min, and a load of 9.8 N. The folding was performed with the hard coat layer on the inside. While checking the number of folding times, the state of the laminated film was visually observed and evaluated according to the following criteria. A (excellent): No breakage (crack) was observed even after repeating 200,000 times or more B (good): When repeated 200,000 times, breakage (crack) was confirmed, but no breakage (crack) was observed when repeated 150,000 times or more and less than 200,000 times C (medium): When repeated 150,000 times, breakage (crack) was confirmed, but no breakage (crack) was observed when repeated 100,000 times or more and less than 150,000 times D (insufficient): When repeated 100,000 times, breakage (crack) was confirmed, but no breakage (crack) was observed when repeated 50,000 times or more and less than 100,000 times E (poor): Breakage (crack) was confirmed when repeated 50,000 times or less

[0073] 2. Production of laminated film [Example 1] As a material for forming a hard coat layer, a solution of HEMA (hydroxyethyl methacrylate) resin (sp value: 11.25 MPa 1 / 2 ), as resin materials for forming the first resin layer and the second resin layer, "resin material 1" and "resin material 4" shown in Table 1 were prepared respectively. The difference in sp value between the hard coat layer and the first resin layer is as shown in the column of "Difference in sp value between the hard coat layer and the resin layer on which the hard coat layer is disposed" in Table 1. "Resin material 1" and "resin material 4" were respectively injected into the inlets of a multi-layer extrusion device equipped with an inlet for the first resin material and an inlet for the second resin material, and a laminate was produced by a T-die of the multi-layer extrusion device. The extrusion was carried out by extruding at a cylinder temperature of 240 °C and a discharge rate of 4.0 kg / h, then extruding into a sheet shape with a T-die at 270 °C, and subsequently cooling with three rolls at 110 °C, 120 °C, and 180 °C. Thereby, a base film (base material) with an overall thickness of 40 μm (thickness of the first resin layer: 10 μm, thickness of the second resin layer: 30 μm) was produced. On the first resin layer of the obtained base material, the "material for forming a hard coat layer" was applied, then heated under the conditions of 60 °C for 1 minute, and then irradiated with ultraviolet light (UVA) under the condition of an integrated light quantity of 2000 mJ / min to cure the coating film of the material for forming a hard coat layer, thereby forming a hard coat layer (thickness: 2 μm) on the base material. Thereby, a laminated film was produced. For the samples of the produced laminated film, the hard coat property was evaluated by measuring the above pencil hardness, and the flexibility was evaluated by performing a bending test. The results are shown in Table 1.

[0074] [Examples 2 to 3 and Comparative Example 1] A laminated film was produced in the same manner as in Example 1 except that the first resin material was changed to that shown in the column of "First resin layer" in Table 1. The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0075] [Comparative Example 2] A laminated film was produced in the same manner as in Example 1, except that the first resin layer was not formed. The obtained laminated film was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

[0076] The details of the materials shown in Table 1 are as follows. · Resin material 1: Acrylic resin (product name HTX-Z, manufactured by Kaneka Corporation). sp value: 9.5 MPa 1 / 2 . Glass transition temperature: 128 °C · Resin material 2: Cycloolefin resin (product name ZEONOR, manufactured by Nippon Zeon Co., Ltd.). sp value: 8.5 MPa 1 / 2 . Glass transition temperature: 163 °C. · Resin material 3: Polycarbonate resin (product name Tafron, manufactured by Idemitsu Kosan Co., Ltd.). sp value: 9.7 MPa 1 / 2 . Glass transition temperature: 150 °C. · Resin material 4: Polycarbonate resin. sp value: 10.5 MPa 1 / 2 . Glass transition temperature: 130 °C. Resin material 4 was prepared as follows. 37.5 parts by mass of isosorbide (ISB), 91.5 parts by mass of 9,9-[4-(2-hydroxyethoxy)phenyl]fluorene (BHEPF), 8.4 parts by mass of polyethylene glycol (PEG) with an average molecular weight of 400, 105.7 parts by mass of diphenyl carbonate (DPC), and 0.594 parts by mass of cesium carbonate (0.2 mass% aqueous solution) as a catalyst were respectively charged into a reaction vessel. As the first stage of the reaction under a nitrogen atmosphere, the heat medium temperature of the reaction vessel was set to 150 °C, and the raw materials were dissolved (about 15 minutes) while stirring as necessary. Next, the pressure in the reaction vessel was changed from normal pressure to 13.3 kPa, and while raising the heat medium temperature of the reaction vessel to 190 °C over 1 hour, the generated phenol was withdrawn outside the reaction vessel. After maintaining the temperature inside the reaction vessel at 190°C for 15 minutes, as the second-stage process, the pressure inside the reaction vessel was set to 6.67 kPa, the temperature of the heat medium in the reaction vessel was raised to 230°C in 15 minutes, and the generated phenol was extracted out of the reaction vessel. Since the stirring torque of the stirrer increased, the temperature was raised to 250°C in 8 minutes, and in order to further remove the generated phenol, the pressure inside the reaction vessel was reduced to 0.200 kPa or less. After reaching a predetermined stirring torque, the reaction was terminated, and the generated reaction product was extruded into water and then pelletized to obtain a polycarbonate-based resin containing structural units derived from a dihydroxy compound at a ratio of BHEPF / ISB / PEG = 42.9 mol% / 52.8 mol% / 4.3 mol%.

[0077]

Table 1

[0078] As is clear from Table 1, in the laminated film of the example of the present invention in which the difference in solubility parameter (sp value) between the hard coat layer and the first resin layer is 1.5 or more, it was found that the hard coat property and flexibility are excellent.

Industrial Applicability

[0079] The laminated film according to the embodiment of the present invention is suitably used for optical members such as polarizing plates and image display devices such as organic EL devices.

Explanation of Symbols

[0080] 1 Laminated film 10 Hard coat layer 20 Base material 21 First resin layer 22 Second resin layer

Claims

1. A base material and a hard coat layer disposed on one surface of the base material, wherein the base material includes a first resin layer and a second resin layer in this order from the hard coat layer side, and the difference in solubility parameters between the hard coat layer and the first resin layer is 1.5 or more. A laminated film.

2. The second resin layer is disposed directly on the first resin layer. The laminated film according to Claim 1.

3. The hard coat layer is disposed directly on the first resin layer. The laminated film according to Claim 1.

4. The difference in glass transition temperature between the first resin layer and the second resin layer is 40°C or less. The laminated film according to Claim 1.

5. The second resin layer contains a polycarbonate resin, the polycarbonate resin contains a structural unit derived from a dihydroxy compound, and the dihydroxy compound is at least one compound selected from the group consisting of isosorbide, isomannide, and isoidide. The laminated film according to Claim 1.

6. The first resin layer contains a polycarbonate resin, and the polycarbonate resin substantially does not contain a structural unit derived from a dihydroxy compound selected from the group consisting of isosorbide, isomannide, and isoidide. The laminated film according to Claim 1.

7. The thickness of the first resin layer is smaller than the thickness of the second resin layer. The laminated film according to Claim 1.

8. The thickness of the first resin layer is 0.5 μm or more and 10 μm or less. The laminated film according to Claim 7.

9. The thickness of the second resin layer is 15 μm or more and 40 μm or less. The laminated film according to Claim 8.

10. An optical member comprising the laminated film according to any one of Claims 1 to 9 and an optical film. An optical member.

11. The optical film includes a polarizer. The optical member according to Claim 10.

12. An image display device comprising the laminated film according to any one of Claims 1 to 9. An image display device.

13. An image display device comprising the optical member according to Claim 10. An image display device.

Images